Brake control devices for preventing locking or sliding of vehicle wheels when the brakes are applied by an operator are well known. Such devices have included means for automatically controlling the release and reapplication of the wheel brake. Such "anti-lock" devices have been used in automotive vehicles such as trucks, truck trailers and buses, as well as in railway cars.
Brake control anti-lock devices have included, for example, rotary inertia type devices sensitive to acceleration and deceleration of a vehicle wheel, which may be installed within the hubs of existing truck-trailer wheels.
Anti-lock devices and systems have been described in a copending patent application, assigned to the same assignee as the present invention, of Mekosh and Hulse entitled "ANTI-LOCK MECHANISM", Ser. No. 026,795 filed Apr. 3, 1979.
A particular type of switching device includes an inertia wheel to open and close valves is described in the aforementioned patent application. Therein, the inertia wheel controls the application of service pressure to the brake to prevent wheel lock-up and may be of the same general type as that used and to be described in connection with the present invention.
In the anti-lock device disclosed in the aforementioned application, the inertia wheel is a switching unit and is connected to rotate with the vehicle wheel about its axis. The switching unit was connected through the wheel to a source of control pressure also located in the axis of rotation of the wheel. This was possible because a hollow tubular structure was located at the axis of the wheel and also inboard of the wheel to receive the connections from the switching unit. This arrangment, however, poses a problem when the means for controlling the control pressure cannot be located at the axis of rotation of the wheel as, for example, when solid drive axles are used as in a tractor or other such similar type vehicles.
It is an object of this invention to provide an improved pneumatic anti-lock system for a vehicle wheel rotatable on a solid or drive axle.
It is a further object of this invention to provide an improved pneumatic anti-lock system for a wheel of a tractor or other such similar vehicle.
It is still a further object of this invention to provide an improved anti-lock system with a switch axially connected outboard to rotate with a vehicle wheel to control pressure located inboard of the wheel by means of a pressure path from outboard to inboard and which is offset from the wheel axis.